Clearfield 161 Has Rice Growers Buzzing

Louisiana rice farmers report that they are pleased with Clearfield 161, the latest version of the herbicide-resistant rice that was developed at the LSU AgCenter. The variety allows farmers to control red rice, which has been their No.1 weed enemy. (Photo by Mark Claesgens)

Rice farmer Danny Koch noticed something special as he piloted a combine the size of a small house through his 82-acre field of Clearfield 161 rice this summer.

“This field was tremendously infested with red rice last year,” said Koch, who farms just north of Eunice. “Look at it this year. There’s not a stalk in here. It’s amazing.”

Credit the emergence of Clearfield 161, a new rice variety released by the LSU AgCenter’s Rice Research Station in Crowley, for Koch’s and other farmers’ clean fields.

Used in combination with BASF’s NewPath herbicide, the Clearfield rice system has shown 99 percent or more control of red rice weeds in fields throughout the U.S. rice belt this year.

Koch put the pencil to his Clearfield 161 harvest data and came up with this: He averaged just over 42 barrels of rice per acre and experienced excellent milling quality. Some other farmers in southwest Louisiana reported even higher yields with Clearfield 161, which was available for commercial use for the first time in 2003.

“I would have made nothing in this field if it hadn’t been for Clearfield 161,” Koch said.

Clearfield 161 got its start when Tim Croughan, an AgCenter scientist at the Rice Station, discovered that by bathing particular rice seeds in ethyl-methane sulfonate (Clearfield 161 comes from the seed of Cypress, another AgCenter rice variety with strong yields and top-notch milling characteristics), he could create microscopic changes in the rice plant’s genetics and increase herbicide resistance.

The end result was that Clearfield 161 became so resistant to the effects of imazethapyr, the active ingredient in the NewPath herbicide, that farmers can spray the red rice weeds in their fields with NewPath and not harm the good rice growing nearby.

Before Clearfield technology, any herbicide that killed red rice weeds also killed the good rice growing next to it. Red rice is a troublesome weed problem in southwest Louisiana . It competes for the same nutrients and hurts both yields and milling quality of the good rice harvested from infested fields.

Clearfield 161 is not a genetically modified crop (GMO) because no gene is inserted into the rice plant. Instead, chemical manipulation is used to encourage mutations in the rice plant’s DNA similar to changes that occur naturally anyway.

“Using ethylmethane sulfonate just makes it more likely for mutations to occur,” said Croughan. The trick is to foster the right mutations that affect the plant’s herbicide resistance.

Top officials with Horizon Ag, a Memphis-based firm that markets Clearfield seed nationally, say they expect to see a big jump in the number of acres planted with the new variety in 2004.

“We expect at least 75,000 acres to be planted in Louisiana in 2004, up from 30,000 acres this year,” said Randy Ouzts, Horizon’s general manager. Nationally, he projects at least 375,000 acres to be planted in 2004, almost double this year’s total.

“Clearfield 161’s milling quality is fine, very good. I haven’t heard one complaint,” said Bill Dore, president of the Supreme Rice Mill in Crowley.

Steve Linscombe, director of the LSU AgCenter’s Southwest Region and a rice breeder, agrees. He said Clearfield 161 will resurrect some poor-performing fields that were economic losers in years past because of severe red rice problems.

“All the results on yields and grain quality look very good,” Linscombe said after reviewing recent LSU AgCenter test data on Clearfield 161. “In some fields this year, farmers had the highest yields they’ve ever had when you consider all their past red rice problems and the losses that can cause.”

Tommy Ellett, co-owner of Angelina Plantation in Concordia Parish, participated in a test with AgCenter rice specialist Johnny Saichuk. Side-by-side fields were planted under similar conditions – one field with Clearfield 161 and the other in the popular Cocodrie rice variety. Both fields historically had severe red rice problems.

In midsummer, Ellett could see the difference at a glance. “We’ve got 99 percent red rice control (on the 161 field). It’s like daylight and dark between the two fields.”

One word of caution: Clearfield 161 seed costs more than many conventional rice varieties, so it may not be a farmer’s best choice in every instance. But proponents say using it could put more cash in a producer’s pocket depending on how severe red rice was in a particular field and to what extent the weeds reduced the yield, grade or the milling quality of the good rice.

Many farmers who used Clearfield 161 this year planted their fields at seeding rates ranging from 80 pounds to as much as 100 pounds an acre. That may be too much. AgCenter experts familiar with the way the Clearfield 161 rice plant grows (it tillers very well just like its parent variety, Cypress) say farmers will probably be able to reduce seeding rates significantly next year without hurting productivity. Lower seeding rates mean lower costs.

One problem to watch for with Clearfield 161 is that the new rice variety is susceptible to sheath blight, a rice disease that flourishes in wet growing conditions.

Linscombe said growers who opt for Clearfield 161 should include an appropriate fungicide in their production programs.

LSU AgCenter rice research, including development of the Clearfield rice technology, is supported in part by the Louisiana Rice Research Board and by check-off funds contributed by rice farmers across the state.

(This article appeared in the fall 2003 issue of Louisiana Agriculture.)